This apparatus pertains to sawmill operations which plane the edges of a cant. In particular, this apparatus pertains to a cant axis alignment device which positions a cant for subsequent feeding through an edger.
A log entering a sawmill initially goes through a head rig where it is sawed into flat pieces of wood of varying thicknesses. These slabs are referred to as cants. The longitudinal edges of each cant are rounded, since each cant is a section which has been cut out of a round log. Each cant must be run through an edger or planer to remove its rounded edge or wane.
A conventional edger-feeder mechanism transports a cant to an edger in-feed position where the cant is fed through an edger. The edger removes the rounded edge portion of the cant, which is referred to as the wane. Some edger systems utilize a wane-scanning system, coupled with a computer, in order more efficiently to edge wood products. A wane-scanning device, such as that disclosed in U.S. Pat. No. 4,298,286 can generate data which may be processed to adjust an edger width, or to adjust the position of a cant upstream of an edger--the desired result being the most efficient and productive edging of a cant to produce the largest possible finished board. Various mechanisms have been devised to transfer a cant from a saw offload conveyor, through a wane-scanning system and then onto an edger in-feed conveyor. A cant is generally transported laterally toward and through a wane-scanner. The cant must then cease lateral movement and begin movement endwise, a change of motion through 90.degree.. Some form of stop-start movement has been utilized to effect this 90.degree. change of cant direction. Wane-scanning generally takes place prior to a cant beginning its endwise movement. The requirement of changing cant movement by 90.degree. has been solved by stopping a cant at the end of one conveyor, moving it through a scanning station, and then positioning the cant on an edger in-feed conveyor while the infeed conveyor is stopped. The conveyor is then started and the cant moves endwise through the edger mechanism.
The described stop-start movement required to move a cant through an edger is difficult to achieve, and produces excessive wear on machinery which is stopped and started under heavy load conditions. Stop-start motion also results in some movement of a cant about its longitudinal axis, which can result in a cant moving through an edger improperly, thereby producing an over-edged, or narrow, board.
A general object of the present invention therefore, is to provide an efficient means of positioning a cant upstream of an edger.
Another object of the invention is to position a cant upstream of an edger through both rotational and translational movement of a cant about its longitudinal axis.
Yet another object of the present invention is to provide a cant transfer apparatus which produces a reciprocating sinusoidal motion with characteristic smooth yet rapid acceleration and deceleration.
A further object of the instant invention is to provide a smooth transition from edgewise to endwise motion of a cant, whereby a cant is accelerated to the speed of an edger in-feed conveyor.
The apparatus of the instant invention utilizes reciprocating sinusoidal motion to move a cant from an intake station through a wane-scanning station and thence to a discharge station in one smooth motion. The apparatus is capable of both translational and rotational movement which allows a cant to be deposited on an edger in-feed conveyor in proper alignment for edging. Reciprocating sinusoidal motion produces smooth rapid acceleration and deceleration which prevents the cant from rotating independently about its longitudinal axis, thereby allowing a more efficient edging operation.
Another feature of the apparatus of the instant invention is that it is capable of accelerating a cant endwise at the discharge station, matching the speed of the edger in-feed conveyor, producing a smooth transition between edgewise and endwise movement.
In an overall picture sense, the apparatus of the invention can be viewed as one wherein all of the actions involved in scanning, positioning and transferring a cant take place with this cant substantially continuously on the fly.
These and other objects and advantages of the instant invention will become more fully apparent as the description which follows is read in conjunction with the drawings.